mysql 联合主键？
第一次听说这个东西，将多列联合起来形成一个主键，为的是行记录整体上不重复，这个不就是2NF的内容吗？
回复讨论(解决方案)
几范式我也忘记了
但是这么做应该可以降低数据库的冗余
当年数据库原理学的也是一头雾水啊...范式定义也忘了
大些的系统经常这么做，使用业务逻辑上的唯一性，而不是数据库系统上的唯一性。
这样更有利于约束业务逻辑，不产生冗余。
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